package org.mirrentools.attendance.console.common;

import java.security.MessageDigest;

/**
 * SHA1加密工具
 * 
 * @author <a href="http://szmirren.com">Mirren</a>
 *
 */
public class SHA1Util {

	/**
	 * 将字符串进行SHA1加密
	 * 
	 * @param str
	 *          字符串
	 * @return
	 */
	public static String encode(String str) {
		if (str == null) {
			return null;
		}
		try {
			MessageDigest messageDigest = MessageDigest.getInstance("SHA1");
			messageDigest.update(str.getBytes());
			return getFormattedText(messageDigest.digest());
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}

	private static final char[] HEX_DIGITS = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

	private static String getFormattedText(byte[] bytes) {
		int len = bytes.length;
		StringBuilder buf = new StringBuilder(len * 2);
		// 把密文转换成十六进制的字符串形式
		for (int i = 0; i < len; i++) {
			buf.append(HEX_DIGITS[(bytes[i] >> 4) & 0x0f]);
			buf.append(HEX_DIGITS[bytes[i] & 0x0f]);
		}
		return buf.toString();
	}

}
